Circuit interrupter



April 1, 1958 J. E. HARDER CIRCUIT INTERRUPTER 5 Sheets-Sheet 1 FiledMay 26, 1955 INVENTOR John E; Harder BY WW AT TORNEY April 1, 1958 1 J.E. HARDER 2,829,218

CIRCUIT INTERRUPTER Filed May 26, 1955 3 Sheets-Sheet 2 April 1, 1958 J.E. HARDER CIRCUIT INTERRUPTER Filed May 26, 1955 3 Sheets-Sheet 5 Fig.5.

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iatented Apr. l, 1958 CIRCUH INTERRUPTER John E. Harder, Swissvale, Pa,assignor to Westinghouse Electric Corporation, East Pittsburgh, Pin, acorporation of Pennsylvania Application May 26, 19255, Serial No.511,204]

4 Claims. (Cl. millild) This invention relates to circuit interruptersin general, and, more particularly to load-break fuse cutouts.

At certain locations on distribution systems it is desirable to have aninexpensive switch for occasional operation. At many of these samelocations it is necessary to have fault-current protection. For thisreason, a fuse cutout with load-break ability would be very desirable.

Fuse cutouts have fault-current interrupting ability. Normally speaking,they do not have load-current interrupting ability. In order to obtainthis ability it is necessary to devise some special arrangement. schemeis to provide mechanical means for breaking tne fuse link at its fusiblesection. A number of manufacturers have exploited various means forbreaking the fuse link. In general, many of these arrangements have beencomplicated, flimsy, and difficult to operate.

It is a general object of my invention to provide an improved mechanicalarrangement for accomplishing the task of rupturing the fuse link at itsfusible section.

Another object of my invention is to provide an improved arrangement forbreaking the fuse link in a fuse cutout, which will be simple, sturdy,sure and will not impair the fault-current operation of the cutout.

Another object of my invention is to provide a loadbreak fuse cutoutsuch that operation thereof is easy and easily understood, with thefusing thereof also being easy of accomplishment. In addition, themechanism of my invention is coordinated with the design such tocompletely eliminate any fouling with the other mechanism occurring.

Another object is to providea load-break fuse cutout with a manuallyoperable load-break lever, which will be sturdy enough to stand theabuses a load-break cutout will receive, and will withstand the ravagesof the elements in the open. The load-break structure will break r thestrongest links within its rating, and will withstand the large jetforces during fault-current interruption.

An additional object of the invention is to provide an improvedload-break arrangement for a fuse cutout, in which the direction of pullis generally downward to facilitate operation, and is also in adirection about the hinge point to maintain the fuse contacts closedprior to fuse-link rupture.

Still afurther object of my invention is to provide an improved rollerarrangement for a manually operable load-break attachment for a fusecutout in which any uneven stress along the fuse link cable iseliminated, and only the fusible section of the fuse link will bebroken.

An ancillary object of my invention is to provide an improved load-breaklever for a fuse cutout having an open-hook portion so that the prong ofthe switch stick may slip therefrom during manual rupturing of the fuselink, so that the book will come free from the handle after the handlehas been pulled far enough to insure that the arc has been extinguished.This, of course, minimizes the jar to the cutout and any probableassociated damage. I

in general, it is an object of my invention to provide a One such 15sturdy load-break lever of such construction that nothing can go wrong,and that there will be no question concerning its proper assembly.

Further objects and advantageswill readily become apparent, upon readingthe following specification, taken in conjunction with the drawings, inwhich:

Figure l is a side elevational View of a load-break fuse cutoutembodying the principles of my invention, and shown in theclosed-circuit position;

Fig. 2 is an enlarged, fragmentary side elevational view, partly insection, of a portion of the fuse holder assembly, indicating therelative position of the parts dur ing manual operation of theload-break lever, following rupture of the fuse link;

Fig. 3 is a top plan view of the load-break lever illustrated in detailin Fig. 4-; V

Fig. 4 is a side elevational view of the load-break lever in detail;

Fig. 5 is a side elevational view of the pin for mounting the roller inthe load-break attachment;

Fig. 6 is a side elevational View of one of the rivet pins for securingthe load-break lever to the toggle-link hinge member;

Fig. 7 is a side elevational view of the roller utilized in theload-break attachment to insure equal stress along the fuse cable;

Fig. 8 is a top plan view of hte toggle-link hinge member;

Fig. 9 is a side elevational view of the toggle-link hinge member ofFig. 8;

Fig. 10 is a detail view of the clamping collar; and

Fig. ll is a diagrammatic view, in side elevation, of the fuse-holderassembly indicating the partially collapsed condition of the toggleimmediately prior to contact separation at the upper fuse contact.

Referring to the drawings, and more particularly to Fig. 1 thereof,there is illustrated a circuit interrupting device 1, being illustratedin the closed-circuit position. As shown, the circuit interruptingdevice 1 is mounted upon a pair of insulator supports 2, 3. Although inthis particular instance being illustrated as mounted upon insulatorsupports 2, 3, it is to be clearly understood that the interruptingdevice 1 may be clamped to a generally vertically upstanding elongatedinsulator. Any suitable mounting, of course, may be employed, and thatshown is merely by way of illustration.

Jutting laterally outwardly from the upper insulator support '2 is anupper stationary contact assembly 4. Also associated with the lowerinsulator support 3, and extending laterally therefrom, is a lowerstationary contact assembly 5.

Referring more particularly to the upper end of the interrupting device1, it will be observed that the upper stationary contact assembly 4includes an inverted U shaped channel member 6, which may be of steelplate and suitably configured. One or more nuts and bolts 10 secureinward portions of the channel member 6 to a metallic base plate 11, thelatter being suitably secured by any suitable means to an adapter 12affixed to the outer end of the insulator support 2.

A line terminal 13 is associated with the channel member 6 and has aterminal bolt 14 associated therewith, which extends through the topportion of the channel member 6 and rigidly secures a resilient contactplate 35 into position. Adjacent the outer end of the contact plate 15is a detent portion 16, which serves to latch the upper contact of thefuse holder in place, as more fully described hereinafter. Also thecontact plate 15 has a suitable post 17 secured thereto, which limitsthe inward travel of the fuse holder.

The lower stationary contact assembly 5 comprises a U suitablyconfigured steel plate having a top wall portion 21 and side wallportions 22. The side wall portions 22 are bent inwardly toward eachother at the base of the assembly 5 and are secured to a base plate 23by one or more nuts and bolts 26. The nuts and bolts 26 also rigidlysecure a flexible contact plate into place. The base plate 23 is securedby any suitable means to an adapter 24, which, in turn, is afiixed tothe outer end of the insulator support 3.

Preferably a laterally extending portion 27 of the configured plate Ztl'supports a line terminal 30 by a terminal bolt 28, the latter alsopassing through an extension 29 of the contact plate 25.

The lower hood 21) has provided on its side walls 22 means providing ahinge pivot 31 for a switch element or fuse tube 32. More specifically,trunnion guide slots 33 are provided in the side wall portions 22 of thelower metallic hood 21), and have offset trunnion bearings or seatsassociated therewith.

The switch element 32 comprises a fuse tube 35, at least the inner wallthereof being formed of a gas-evolving insulating material, so that areextinction will be facilitated. Extending out of the lower, open end ofthe fuse tube is a fuse link cable extension 36. This cable extension 36is a portion of the fuse link, generally designated by the referencenumeral 40, and enclosed within the fuse tube 35, having at the upperend thereof a fusible portion 41, as well understood by those skilled inthe art.

The end of the fuse-link cable extension is secured by a wing bolt 42 toa toggle-link hinge member 43, shown more in detail in Figs. 8 and 9 ofthe drawings.

Disposed at the upper end of the fuse tube is a metallic terminalferrule 44, which has integrally formed therewith a contact latchingportion 45, which latches under the contact plate 15, as shown in Fig.1, against the stop 17 in the closed-circuit position of the device.Integrally formed with the metallic terminal ferrule 44 is an operatingring 46 to render the device suitable for switch-stick operation.Threaded into the upper end of the terminal ferrule 44 is an externallythreaded cap 50, which secures the upper end of the fuse link intoplace, as well understood by those skilled in the art.

Disposed adjacent the lower end of the fuse tube 35 is a clamping collar51, shown more clearly in detail in Fig. 10 of the drawings. Theclamping collar 51 en circles the fuse tube 35, and is clamped theretoby a clamping bolt 52, which passes through suitable apertures 53provided in the leg portions 54 of the clamping collar 51. Additionalapertures 55 are provided at the extreme ends of the leg portions 54 toencircle trunnions, or stub shafts 56, integrally formed with thetoggle-link hinge member 43. This provides a pivot connection betweenthe toggle-link hinge member 43 and the clamping collar 51 with the fusetube 35, which together constitute a unitary assembly. A name plate 57may be secured externally of the clamping collar 51, and likewisesecured into place by the clamping bolt 52.

Referring more specifically to Figs. 8 and 9, which illustrate thetoggle-link hinge member 43 in detail, it will be observed that aneyelet 61 is provided, enabling the prong of a switch stick to beinserted therein so that the switch element 32 may be bodily lifted outof the trunnion bearings 34 following fuse operation and dropout actionfor a re-fusing operation. Also the togglelink hinge member 43 isprovided with trunnions, or stub shafts 62, which cooperate with thetrunnion bearings 34 provided in the side wall portions 22 of the lowerhood 20. A contact portion 63, more clearly shown in Fig. 9 of thedrawings, cooperates with the flexible contact plate 25 in a manner moreclearly shown in Fig. 1 of the drawings.

In the closed-circuit position of the device, as illustrated in Fig. 1,the circuit extending through the device includes, briefly, lineterminal 13, upper contact plate 15, contact 45, terminal ferrule 44,fuse link 40, toggle-link hinge member 43, contact portion 63, flexiblecontact plate 25 to lower line terminal 30. The fuse tube 35 and theclamping collar 51 rigidly secured thereto constitute a unitaryassembly, which may be considered as a toggle link, generally designatedby the reference numeral 64 and cooperating with the toggle-link hingemember 43 to form a toggle, generally designated by the referencenumeral 65, which is in the slightly underset position, as indicated inFig. 1. A line of action 66 interconnecting the hinge pivot 31 and thecontacts 45 indicate the underset condition of the toggle in theclosed-circuit position of the device, as illustrated in Fig. 1.

As more fully explained in U. S. patent application Serial No. 261,686,filed December 14, 1951, now United States Patent 2,734,964, issuedFebruary 14, 1956, to Andrew W. Edwards and William J. Paxton, andassigned to the assignee of the instant application, upon overload orfault current passing through the device 1, fusing the fusible section41., the cable extension 36' will become slack and will enable thetoggle 65 to collapse, as indicated in Fig. 11, thereby permitting thefuse-holder assembly 32 to drop downwardly and outwardly about the hingepivot 31 to the fully open disconnected position.

An operator must then remove the fuse-holder assembly 32 from thetrunnion seats 34 by insertion of the prong of a switch stick into theeyelet 61 and removing the fuse-holder assembly 32 to a safe position,where re-fusing may take place. Upon reassembly, using the same eyelet61, the operator may then remove the prong of the switch stick from theeyelet 61 and place it in the operating ring 46, swinging the fuseassembly about the hinge pivot 31 in a counterclockwise direction to theclosed position, as shown in Fig. 1.

For certain infrequent operations, it may be desirable to open theconnected circuit when there is no overload or fault current existing onthe line. Previously, it has been customary for an operator to simplyinsert the prong of his switch stick into the eyelet 46 and yank thefuse-holder assembly 32 forcibly open about the hinge pivot 31. However,as the power requirements increase, with the device 1 carrying thehigher current ratings at higher voltage, the resulting are between theseparated contacts 15, 45 under such circumstances is hazardous. Such anare not only damages the contact surfaces, but is liable to be blown bythe wind to adjacent apparatus and cause a fault on the apparatus.

Consequently, it is desirable to break such a load current of valueinsufiicient to effect fusion of the fusible section 41 by a mechanicalarrangement, so that the fusible section 41 will be broken interiorly ofthe fuse tube 35 and are extinction will occur interiorly of the fusetube 35 and not between the contacts 15, 45.

Certain arrangements have been proposed heretofore, but they have eitherbeen complicated, flimsy, or have not been operable in a directionconvenient for an operator. In certain of the devices proposed, theload-break lever has even had portions extending over the open, lowerend of the fuse tube to interfere with the escape of arc gases from thefuse tube during a fault operation. In addition, certain of the priorart devices have not had an adequate mechanical advantage for theoperation of their load-break lever.

In the load-break arrangement of the present invention, there isprovided a load-break lever 70, more clearly shown in detail in Figs. 3and 4 of the drawings. The load-break lever has a handle portion 71 withan open hook portion 72, which is a distinct advantage inasmuch as itimmediately disconnects the prong of the switch stick, manipulated bythe operator, from the device 1 following fuse rupture, so that no shockis exerted upon the interrupting device 1 at the end of the pull exertedby the operator. The load-break lever 70 of the device is pivotallyconnected to a laterally extending U-shaped portion 73 of thetoggle-link hinge member 43. Rivet pins 74, shown in detail in Fig.6,.of the drawings, pivotally connect a bifurcated portion 75 of theload-break lever into place. A roller 76, shown in detail in Fig. 7 ofthe drawings, is positioned between the legs 80, 81 of the bifurcatedportion 75 of the load-break lever 70 by a rivet pin 82, more clearlyshown in Fig. 5.

The load-break lever 7% does not interfere in any way with normalfault-current operation of the device 1.

When, however, an operator desires to open the circuit 1 at a time whenthe current passing therethrough is insufiicient to result in fusion ofthe fuse link 40, he merely needs to put the prong of his switch stickinto the open hook portion '72 of the load-break lever 78 and pulldownwardly until the slack is out of the fuse-link cable 36. Theoperator then gives a good hard pull in a downward direction followingthrough with the motion. As shown in Fig. 2 of the drawings, thedownward pull on the loadbreak lever causes the roller 76, which extendsover the cable extension 36, to forcibly pull downwardly on the cableextension 36' to physically rupture the fusible section 41 of the fuselink 40. This condition is illustrated in Fig. 2 of the drawings, wherethe toggle 65 is still in its stiff-leg position, and where theload-break lever has been moved far enough down so that an arc gap ofsay an inch, or an inch and a half, exists within the fuse tube 35.Further downward travel of the load-break lever 70, as exerted by theoperator, rapidly elongates the arc gap within the fuse tube 35,facilitating arc extinction. Consequently, by the time that the toggle65 collapses, as shown in Fig. 11, the arc has already been extinguishedwithin the fuse tube 35, and there is no possibility of any arcingoccurring between the contacts 15, 45 of the device.

It will be noted that the fuse cutout is assembled in its customaryfashion, and that the cutout will carry continuous current in the normalmanner. Fault current can be interrupted and dropout action is similarto a standard type of fuse-holder assembly. It will be observed that asthe load-break lever 70' is pulled downwardly the roller 76 is pushed ina general downward direction. The fuse link, which is fastened rig-idlyat the top of the fuse tube 35 and rigidly under the wing nut 42, iselongated by the downward motion of the roller 76. This motion continuesin this direction until the fuse link 40 is ruptured. The fuse link 40always ruptures at the fusible section 41, inasmuch as the relativelylarge radius of the roller 76 exerts a uniform even tension along thefuse link cable extension 36'.

It is also to be noted that in pulling in the downward direction on thehandle 71, the moment of forces around the hinge pivot 31 is in theproper direction to keep the fuse holder 32 in place as long as the fuselink 40 has not been broken. The moments on the handle '71 and on thehinge 43 are such that the bottom contact pressure between the trunnions62 and the trunnion bearings 34 will also be maintained until after thefuse link 40 is broken.

After the fuse link 40 is broken, the handle 71 continues to rotateabout the pivot 74, but the motion becomes complicated some by themotion of the toggle-link hinge member 43 itself. As the tension in thefuse link 44 has become very small, the motion is now governed by thelaws of dynamics rather than by the laws of statics. That is to say, ananalysis of the motion statically, increment by increment, no longeradequately describes the motion. All parts of the fuse-holder assembly32 are now in mo tion. The toggle-link hinge member 43 is rotating in aclockwise direction about the hinge pivot 31. The handle 71 is rotatingin a counterclockwise direction about the pivot 74, which in turn isrevolving in a clockwise direction about the hinge pivot 31. In otherwords, it is a part of the hinge element 43. The fuse tube 35 and theclamp assembly 51 stays in a generally vertical position because of itshigh moment of inertia around the hinge point 60. Because the hingepoint 60 is part of the togglelink hinge member 43, the fuse tube 35 andthe clamp assembly 51 is also moving in a generally downward direction.

Because of the force which must be exerted on the handle 71 in order tobreak the fuse link 40 in the first place, this dynamic part of themotion, which follows rupture of the fuse link 40, is very fast. Thiscauses rapid elongation of the arc within the fuse tube 35 andsubsequent quick interruption of the load current.

The rcller76 is incorporated in the assembly because it is necessarythat the greatest force exerted on the fuse link 40 be exerted in thefusible section it of the link 40. If a roller 76 were not used, therewould be a stress concentration in the link 40 between the roller andthe wing bolt 42). This would be a very undesirable situation becauserupture of the fuse link 40 in this section would mean failure of thedevice to interrupt load current. Since the fusible element 41 isnormally the weakest section of the link 40, even tension throughout thelength of the link 40 will cause rupture at the fusible element 521resulting in proper load-break operation.

Throughout its construction this device does not subject the link to anyradius less than inch except in the clamping device. This is done toeliminate bending stresses, or any stress concentration, in the lengthof the link, and subsequent probability of damage to the link.

In the illustrated design the handle 71 is hinged to the hinge element43 instead of to the fuse tube and clamp assembly, as in some of theprior art. The advantage of this is that the bottom hinge 43 is subjectto a moment in a counterclockwise direction while the fuse link is beingruptured. This counterclockwise moment assures maximum contact pressureat both top and bottom contacts during the break operation.

The open end handle '71 permits a good strong pull with follow-through,because the hook will come free from the handle 71 after the handle 71has been pulled far enough to assure that the arc has been extinguished.This minimizes the jar to the cutout and any possible associated damage.A large wing bolt 42 has been provided as a clamping mechanism on thisload-break cutout to assure that the lineman can make the bottom end ofthe fuse iink good and tight. The serrated base under the wing bolt 42assures that if the wing bolt has been properly tightened, the fuse linkcable 36 will not slip during the load-break operation.

From the foregoing description of the invention it will be apparent thata strong, sturdy, load-break mechanism is provided as a part of thefuse-holder assembly 32, and not as a flimsy attachment which may besecured to existing fuse-holder assemblies. The roller 76 assures eventension along the fuse-link cable 36 so that rupture always occurs atthe fusible section 41. Also the roller '76 and all parts of theload-break arrangement are disposed away from the lower, open end of thefuse tube 35 in the closedcircuit position of the device, as illustratedin Fig. l. There is no portion of the load-break attachment which isdirectly under the lower, open end of the fuse tube 35 as exists in someof the prior art arrangements. in addition, by having the pivot point 74of the load-break lever '70 substantially along the axis of the fusetube 35, as illustrated in Fig. 1, and not in front of the fuse tube 35,or to the right of the fuse tube 35, with reference to Fig. 1, aconsiderable mechanical advantage is obtained, which would not beobtained should the pivot location 7 be moved toward the right, asviewed in Fig. 1.

Although there is shown and described a specific loadbreak structure, itis to be clearly understood that the same was merely for the purpose ofillustration, and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the invention.

I claim as my invention:

1. A load-break fuse cutout including a pair-of spaced contactassemblies, a collapsible fuse holder assembly electrically bridgingsaid spaced contact assemblies in the closed circuit position thereof,said fuse holder assembly including a toggle-link hinge member, one ofsaid contact assemblies pivotally supporting said toggle-link hingemember, said fuse holder assembly also including a fuse tube and aclamping member thereabout, means pivotally mounting said clampingmember to said toggle-link hinge member, a fuse link extending throughsaid fuse tube, a manually operable load-break lever pivotally mountedon said toggle-link hinge member and having an engaging portion for saidfuse link to tension the latter and so effect its rupture, fasteningmeans on said toggle link hinge member, and the fuse link extending outof said fuse tulre around the engaging portion of said load-break leverand secured to said fastening means.

2. A load-break fuse cutout including a pair of spaced contactassemblies, a collapsible fuse holder assembly electrically bridgingsaid spaced contact assemblies in the closed circuit position thereof,said fuse holder assembly including a toggle-link hinge member, one ofsaid contact assemblies pivotally supporting said toggle-link hingemember, said fuse holder assembly also including a fuse tube and amember secured thereto, means pivotally mounting said member to saidtoggle-link hinge member to form thereby a collapsible toggle, a fuselink extending through said fuse tube, a manually operable loadbreaklever pivotally mounted on said toggle-link hinge member at a point offof the pivot axis of said one contact assembly, and said load-breaklever having an engaging portion for said fuse link to tension thelatter and so effect its rupture.

3. A load-break fuse cutout including a pair of spaced contactassemblies, a collapsible fuse holder assembly electrically bridgingsaid spaced contact assemblies in the closed circuit position thereof,said fuse holder assembly including a toggle-link hinge member, one ofsaid contact assemblies pivotally supporting said toggle-link hingemember, said fuse holder assembly also including a fuse tube and amember secured thereto, means pivotally mounting said member to saidtoggle-link hinge member to form thereby a collapsible toggle, a fuselink extending through said fuse tube, a manually operable load-breaklever pivotally mounted on said toggle-link tinge member at a point olfof the pivot axis of said one contact assembly, and said load-breaklever having a roller to engage said fuse link to tension the latter andso eifect its rupture.

4. A load-break fuse cutout including a pair of spaced contactassemblies, a collapsible fuse holder assembly electrically bridgingsaid spaced contact assemblies in the closed circuit position thereof,said fuse holder assembly including a toggle-link hinge member, one ofsaid contact assemblies pivotally supporting said toggle-link bingemember, said fuse holder assembly also including a fuse tube and amember secured thereto, means pivotally mounting said member to saidtoggle-link hinge member to form thereby a collapsible toggle, a fuselink extending through said fuse tube, said toggle-link hinge memberhaving a bifurcated portion forming legs Which straddle said fuse tube,a manually operable load-break lever pivotally mounted to the legs onsaid toggle-link hinge member at a point oif of the pivot axis of saidone contact assembly, and said load-break lever having an engagingportion for said fuse link to tension the latter and so effect itsrupture.

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